In the field of aircrafts, for instance helicopters, it is known to use hollow rollers to improve the lightness of a piece of equipment, such as a gearbox, and to lower the risks of skidding between the outer surface of a roller and the corresponding raceway of a bearing ring.
U.S. Pat. No. 3,410,618 discloses an anti-skid bearing where hollow rollers are used with a hollowness range between 60% and 70%. U.S. Pat. Nos. 8,210,754 and 8,328,429 disclose radial roller bearings having massive rollers to sustain a load and hollow rollers to avoid slippage or skidding between rollers and raceways of the rings of the bearing.
Known hollow rollers are generally manufactured by forging.
A key feature of a hollow roller is the coaxiality between its inner and outer radial surfaces. Actually, when a bearing rotates at a speed of about 30,000 rpm, its rollers rotate at a much higher speed, in the range of 300,000 rpm. Thus, if the inner and outer surfaces of a hollow roller are not precisely centered on a common axis, there exists a risk of unbalance of the roller which might destroy it or damage the rings raceways, in case of high rotation speed of the bearing.
Similar problems might occur with roller bearings including hollow rollers in other technical field, outside the aerospace domain.